Mine anchor-line cutter



Sept '17, 1957 .R. TEMPLE I MINE ANCHOR-LINE CUE'TER 2 Sheets-Sheet .l

7 Filed Oct. 2, 1943 INVENTOR. flag 7" ArTOR/VEYJ.

. q 1957 R. TEMPLE 2,806,442

' MINE ANCHOR-LINE CUTTER Filed Oct. 2. 1943 2 Sheets-Sheet 2 asserts MINE Auction-Linn cur'rna Robert Tempie, Pittsburgh, Pa., assigns: to Temple Velocity Equipment, ind, Wiimington, Bah, a corporation of Delaware Application Uctober 2, 1943, Serial No. 94,663

29 Claims. (Cl. 1l4-22ll) This invention relates to devices for cutting the lines by which explosive mines are anchored below the surface of oceans and other bodies of water, and more particularly to such devices in which the cutting member is actuated by an explosive charge.

In mine sweeping operations the mines encountered may be anchored by wire cables, by soft chains, or by hard or case-hardened chains. No satisfactory cutting device known heretofore has been able to sever all three types of anchor lines. This has been due chiefly to the fact that when the cutter is made powerful enough to cut soft chains, the most difficult lines to sever, the device must be very strong and heavy to withstand the tremendous shock to which it is subjected when it cuts only a small cable. As a result, the cutter not only is expensive, but also too heavy for practical use. On the other hand, if a lighter weight cutter is used which is capable of cutting cables and hard chains, it is likely to fail to cut through a soft chain which it may encounter, and merely clamp onto it with all the disadvantages and dangers that arise when a mine thus becomes attached to the sweep line. Other weaknesses of known types of cutters include their too frequent failure to operate when they should, and their occasional tendency to catch on the mine anchor lines and prevent the lines from entering the cutting recesses.

It is among the objects of this invention to provide a mine anchor-line cutter which can out both hard and soft chains and also cables, which is relatively small and lightweight, which can not be fouled by an anchor line, and with which the chance of not operating is practically negligible.

In accordance with this invention, a frame is provided with a recess for receiving a mine anchor-line, and with a cutting member that is adapted to be driven into the recess for severing the line. The cutting member is driven by an explosive charge that is fired by a combination of mechanical and hydraulic means so that mud and the like will not foul the firing mechanism. Thus, a hydraulically actuated piston actuates a member that transmits the hydraulic pressure to a firing pin which explodes the charge. The hydraulic pressure is obtained by a normally retracted spring-pressed plunger that, when released by a trip membcr actuated by an anchor line in the cutting recess, forces sea water against the piston. The end of the cutting recess opposite to the cutting member is provided with a removable anvil against which the cutting member operates. This anvil may normally be held in place by a shear pin, but the impact of the cutting member against the anvil causes it to shear oif the pin so that both the cutting member and the anvil shoot out of the frame and are lost. This makes it unnecessary to provide a heavy frame to stop the cutting member, and thereby reduces the weight and cost of the cutter.

The frame is rigidly mounted on a stabilizing fin by which it is held substantially horizontally in the water with the entrance to its cutting recess facing forward. The front of the fin is fastened to the sweep line, and the cutter frame is disposed at an acute angle to the front edge of the fin from which it projects outwardly. The entrance to the cutting recess extends outwardly from the front edge of the fin so that an anchor line sliding along against the front of the fin is guided directly into the recess without exerting any appreciable vertical. force on the front of the apparatus. After the apparatus has been fired, a gate closes the entrance to the cutting recess so that the next anchor line encountered will pass over the cutter to the next cutter located further out on the sweep line. This gate may be held open by the shear pin that holds the anvil in place so that when the pin is sheared off, the gate is closed by a spring.

The preferred embodiment of the invention is illustrated in the accompanying drawings in which Fig. l is a rear view of my cutting device; Fig. 2 is a front view; Fig. 3 is a horizontal section taken on the line IIIIII of Fig. 1; and Figs. 4 and 5 are vertical transverse sections taken on the lines IV-IV and VV, respectively, of Fig. 3.

Referring to the drawings, a stabilizing fin 1 has its longitudinal axis extending in the direction in which the device is pulled through the water by a sweep line 2 extending backwardly and laterally from a mine sweeper in a well-known manner. The front edge of the fin is inclined to its longitudinal axis the same degree as the sweep line. This front edge is provided at opposite ends with integral ears 3 and 4 that hook over the sweep line and extend rearwardly parallel to the fin. Bolts 6 extend through the fin and these cars hold the fin on the sweep line, while a tapered collar 7 (Fig. 3) clamped on the line at the far side of the fin keeps it from sliding outwardly along the line and yet permits it to rotate thereon so that it can stay horizontal.

Rigidly mounted on the front portion of the fin is the metal frame 10 of the cutting device. The longitudinal axis of this frame is substantially perpendicular to the longitudinal axis of the fin, and the frame is set back from the front corner of the fin so that some of the fin projects ahead of the frame and only a small amount of the frame projects outwardly beyond the front edge of the fin. As shown in Fig. 3, the front side of this outwardly projecting portion of the frame is provided with a cutting recess 11 that extends longitudinally of the frame away from the fin. The entrance to this recess is at its fin-end, and the inner side of the entrance is substantially flush with the front edge of the fin. It will be seen that the general shape of the frame is similar to a hook lying on its side.

The frame is provided with a longitudinal bore extending inwardly from the inner end of the cutting recess, and this bore normally contains a cutting punch 12 that is held retracted in proper position by a shear pin 13 extending through it and the surrounding frame. At the other end of the recess there is another bore 14 in axial alignment with the punch and extending out through the end of the frame. This bore is at least as large as the punch-receiving bore and normally contains an anvil 16 in the form of a metal plug which is held in place by a shear pin 17 that extends through it from front to back. The pin also extends forward through the front of the frame and is provided with a slotted head 18. The inner or rear end of the pin is threaded into the anvil and projects therefrom into an enlarged bore 19 in the rear portion of the frame.

When a mine anchor line 21, across which the sweep line and fin have been dragged, is caught in the cutting recess it is cut by the punch which is driven against it by the force of an explosion from a cartridge 22 removably mounted in a small bore in the frame at the inner end of the punch. During cutting, the mine line is backed up by the frame above and below the cutting 3 recess,'and by anvil 16 in the path of the punch. To explode the cartridge,-a firing mechanism is mounted in the inner end of the frame. This mechanism includes a breech block 23 which is removably mounted in a slot in the top of the frame by means of a screw 24 and a couple of dowel pins 26. This block is provided with a passage 27 "in axial alignment with the cartridge; the cartridge end of the passage being'of materially reduced diameter.

Slidably mounted in this 'passageis a firing pin 28 the inner end 'ofwhich is provided with four laterally projectingwings29 that engage the wall er the passage and guide the pin therein. The pin is urged inwardly by an encirclingcofl spring 31 compressed-between the wings and the reduced end'of the passage. The opposite ends of the wings engage *theside of the front end 'of, a lever 32 mounted'ina'transverse slot '33 in the inner end of the breech block. The central-portion -of-this' lever is pivotally mounted on a vertical pin "34 so that it can swing toward and away from the cartridge. f There'ar portionof the blockis provided with a passage36 parallel to the firing pin passage and containing -'a piston 37 .that engages-thesamesideof the lever as the: pin, but 'at the opposite -end-thereof. The piston extends only about half way through passage 36, the rest of which is reduced in diameter slightly so that the "piston can not escape from the passage. It'will be seenthat when-the piston is' m'oved towardthe lever it will'rock the lever 'on its pivot; and-thereby force the firing'pin against-the-cartridg'e wh'ieh will thereby befexploded todrive the cutting'punch into the cutting recess.

To prevent the piston from being-'moved accidentally, and thereby causing the cartridge to be discharged, the firingniechanism is so formed thatit can not be'operated unless thepistonpassage behind thepiston is full of water. Thisoccurs-only when the cutter is in the ocean or other bodyof "water in which it is beingused. To force'the water againstthe piston'so that it will be actuated, a plunger is mountedin the frame in'axial'alignmen't with the piston; This plunger hasa rectangular portion 38 thatis'slidable-in a guiding slot 39 eXtending-lengthwiseof the backside of the frame. A retaining pin 41 extends across theslotsubstantially in engagement with the rear side of this rectangular portion to help hold the plunger in'the slot. Theplunger is also held in place by a-rod 42 connected toits rear end and slidably mounted in a-bore 43 in theframe behind'the anvil; The plunger'is urged toward the breech block by a coil spring-44 encircling'the rod'and' compressed between the plungers rectangular po'rtion-and theportion 'of the'frame encircling therod. -The t plungennormally isheld in retracted position, with the s'p'ring compressed, by means of a trip'pin '46 ofsmall di ameter extending through a central passage from the front of the frame and across the cutting recessandinto a transverse openingin-the plunger rod. The front end ofthe'plungerhas a cylindrical head'47 whichenters the rearend of piston-passage 36 when the'plung er is released, and thereby forces the water in thepassage against the pistonto move it ahead against lever 32.

If'the'plungeris accidentally released when the apparatus is-outof the water, the plunger will not actuate the piston because itshe'ad 47 'is shorter thanthe'empty part-ofthe piston passage, so the rectangularportion 38 of-theplunger will strike-the breech block before the headcan strike the plunger. To retract or cock the plunger it is'pushed backwardly by anysuitable tool (not shown) forced againstastud 48 projecting fromthe back of the plunger; When incocked position,-a'safety pin 49 is inserted in whole through the frame witha portion of the pin directly in front of the plunger. 7 This pin'is not removed-until'trip'pin46 hasbeen inserted in the plunger rod andfithe apparatus "is "'aboutto be lowered into the water'.-" r

'When'a'mirie anchor line ente'rs the cutting 'recess'it fen'gages"'the"'trip pin, the front en'd of which is "lield'in fixedpdsitidn'in' a manner about to be described. 'As'the front end of the pin therefore can not move when the mine line bends the pin back against anvil 16, the rear end of the pin is pulled out-of the plunger rod opening, thus releasing the plunger. The released plunger actuates the firing mechanism, and the force of the explosion builds up until sufiicient to cause the cutting punch to shear olf pin 13. The punch then shoots forward, and in cutting the mine line it also shears off the portion of the trip pin in the cutting recess and thus permits the opposite ends of the pin to be removed from the frame when the; apparatus is prepared for cutting again. The impact of the punch against the anvil generally will be great enough to shear off pin 17 so that both punch and anvil will shoot out of the outer end of the frame, and, of course,- be lost. This is a small price to pay, however, for a universal cutter of small size and light weight.

At it is necessary to prevent the cutter from catching on another mine anchor-line after the cutter hasbeen fired, means is provided for closing the entrance to the. cutting recess after a line has'been cut therein; The next anchor-line will therefore pass overtheprojecting'end of the cutter frame and slide along the sweep line until it 1 fastened to the front of the frame inside the gate and' that hasits inner end pressing rearwardly against the inner endof the gate. The gate normally is held open by the head18 of the anvil shear pin which projects over the outer 'endof the gate and'holds it against the frame. When I this pin issheared off, itshead releases the gate which is s'n'ap'pedshut by the leaf spring. While the gate is open it'helps guide a mine anchor-line into the cutting'recess. Beingbifurcated and wider than the cutting punch, it can close and straddle the punch if for some reason thepunch fails to-leave the frame. The headed front end of trip pin 46, bears against the front surface of the frame by which it is held in fixed position until the trip pin has been cut by the punch. To permit the trip pin to be put 7 in place and removed therefrom, the gate and spring 53 are provided'with enlarged'openings 54 and 55, respec tively, adjacent the head of the pin.

"Although a-mine anchor-line is shown as being a cable 21, it -will beunderstood that it may be either a hard or a soft chain, either of which will be cut by my cutting device as easily as 'a cable. In'the 'caseofa hard chain the cutting action is more in the-nature ofa breaking, because the impact of-the punch against a link causes the link to snap apart like a piececf glass. Due to'the construction'of the firing mechanism it is not necessary for the firing'pin to'fit passage '27 like a piston, so there is little danger of the pin becoming stuck by mud and the like in the passage. The alignment of the front'of the fin with the-sweep line, and the position of the cutting recess relative to the front of the fin' permit mine lines to enter the recess without becoming caught on the fin'or cutter frame.

According to the provisions of the patent statutes, I haveexplained theprinciple and construction of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire-to have it understood that, within the scope of the appended claims, the invention -may he practiced otherwise than'as specifically illustrated and described. 'I-claim': a a

1. Amine anchor-line cutter comprising a trauma movable cutting member therein, said-frame being pro vided with a recess adjacent the cutting end of said member'for'receiving 'a mine line, means adapted "to" receive ane'xplosive charge adjacentthe' oppositeend'cf the cutting member, a firing pin for exploding the charge to actuate the cutting member, a piston, spring-actuated means for forcing water against the piston to move it, a movable member actuated by said piston for actuating the firing pin, a trip pin extending across said recess for holding said spring-actuated means in cocked position, a gate pivotally connected to the frame beside said recess, means normally holding said gate open, one end of said trip pin being held in fixed position by the portion of the frame adjacent said gate, said gate-holding means being adapted to be released by said cutting member when the latter cuts the line, and means for swinging the released gate across the entrance to said recess.

2. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a firing pin for exploding the charge to actuate the out ting member, hydraulic pressure actuated means, and a pivoted lever for transferring the force of said hydraulic pressure actuated means to the firing pin for actuating the pin.

3. A mine anchor-like cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a firing pin for exploding the charge to actuate the cutting member, a pivoted lever having one end for actuating the firing pin, and hydraulic pressure actuated means for operating against the opposite end of the lever.

4. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a firing pin for exploding the charge to actuate the cutting member, a piston, spring-actuated means for forcing water against the piston to move it, a movable member l actuated by said piston for actuating the firing pin, and means operable by said mine line for releasing said springactuated means.

5. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a firing pin for exploding the charge to actuate the cutting member, a pivoted lever having one end for actuating the firing pin, a piston at the other end of the lever, springactuated means for forcing water against the piston to move it, and means operable by said mine line for releasing said spring-actuated means.

6. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a firing pin for exploding the charge to actuate the cutting member, a passage communicating at one end with the firing pin and open at the other end, a lever pivoted in said passage with one end adjacent the firing pin for actuating it, a piston adjacent the side of the other end of the lever, spring-actuated means for forcing water against the piston to cause it to swing the lever, and means operable by said mine line for releasing said spring-actuated means.

7. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a passage communicating with one end of said charge-receiving means, a firing pin in said passage for exploding the cha ge to actuate the cutting member, laterally projecting guide members connected to said pin and centering it in said passage, hydraulic pressure actuated means, and a movable member for transferring the force of said hydraulic pressure actuated means to the firing pin for actuating the pin.

8. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a reciprocable firing pin for exploding the charge to actuate the cutting member, a piston mounted for movement in a direction substantially parallel to the direction of movement of said pin, a lever having the opposite ends of one of its sides substantially engaging said pin and piston, means pivoting the lever between the pin and piston, and means for forcing water against: the piston to move it toward the lever.

9. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a reciprocable firing pin for exploding the charge to actuate the cutting member, a piston mounted for movement in a direction substantially parallel to the direction of movement of said pin, a lever having the opposite ends of one of its sides substantially engaging said pin and piston, a normally retracted spring-pressed plunger mounted substantially parallel to the direction of movement of the cutting member and adapted to force water against the piston to move it toward the lever, and means operable by said mine line for releasing said plunger.

10. A mine anchor-line cutter comprising 'a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a firing pin for exploding the charge to actuate the cutting member, a piston, spring-actuated means for forcing water against the piston to move it, a movable member actuated by said piston for actuating the firing pin, means operable by said mine line for releasing said spring-actuated means, and means stopping said spring-actuated means before it can strike the piston.

11. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a breech block removably mounted adjacent said charge-receiving means, said block being provided with a plurality of passages containing a firing pin and a piston and a movable member for transferring motion from the piston to the pin to actuate the pin, and means for forcing water against said piston to actuate it.

12. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end of the cutting member, a breech block removably mounted adjacent said chargereceiving means, said block being provided with a pair of substantially parallel passages connected at one end by a cross passage, a firing pin mounted in one of the parallel passages for exploding said charge to actuate the cutting member, a piston disposed in the other parallel passage, a lever pivotally mounted in the cross passage with its opposite ends adjacent one end of the piston and firing pin, and means for forcing water against the other end of the piston to move it toward said lever.

13. A mine anchor-line cutter comprising a movable cutting member, means adjacent the cutting end of said member for catching a mine line and holding it in position for cutting, means adapted to receive an explosive charge adjacent the opposite end ofthe cutting member;

' e ch tblq r r m veh y; mounted d n sa har ting member, apiston disposed in the-other parallel passage, a lever vpivotally amounted in the cross passage withfitsopposite.ends adjacent one-.end ofthepiston and firinig gpin, a-normally retracted spring;pressed plunger spaced from theoppositeend of :the piston in axial alignment with the zpiston receivingpassage, and means operableby said mine line for releasing said plunger wherebyitforces water against the adjacent end of the piston to move it,- i said vplunger being 4 provided with an .en1;a1 gement thatist rilfes t'he breech block: and stops the plunger beforel-it eanstrike the piston. N

14. A mine anchor-line cuttercomprising -a movable cutting.member, -.means adjacent the-tcutting end of said member-for Icatching a minevline and holding it in positiorrfor cutting, meansadapt'ed to receive an explosive charge 'adjacent the opposite endof the cutting member, a firingpin for exploding the charge to actuate the cutting membenajpiston,spring-actuated means'for forcing water against the pistontomoveih'a movlable member actuated by said piston for actuating the firing pin, said springactuated means being providedwith an op ening, a trip pin. projecting into saidropening for holding the springactuated means in cockedposition, and means for holding the other end of the trip pinin fixed position, said trip pinbeingadapted to be engaged and bent by said mine'line wherebyvit is Withdrawn from said opening to release.saidspring actuated means. w

15. Amine anchor-line cuttercomprising a frame, a free cutting member slidablymounted in the frame, an anvil spaced from the cutting end of said member, means normally holdingthe anvil in operative position in the frame meansfladaptedto receive an explosive charge adjacent the opposite end of the cutting member, means forf guidinga mine line into the space between the cutting inembe'riand anvil, and means for exploding said charge to drive the cutting member through said line and against the anvil, said anvil-holding means releasing the anvil when itiist struck by-the cutting member, whereby the cutting "member and anvil leave said frame.

16. A mine-.anchor-line cutter comprising a frame, a

free cutting'member slidably mounted in the frame, an anvil spaced from the cutting end of said member, shearable means normally holding the anvil in operative positionin thefrarne, means for guiding a mine line into the space between the cutting member and anvil, and explosive .means for driving the cutting member through said line and against the anvil, the impact against the anvil causing it to shear off said shearable means and t-o be ejected from said frame by the cutting member.

17. A mine anchor-line cutter comprising, a frame, a freecutting'member slidably mounted in the frame, an anvil, spaced fromthe :cutting end of said member, a shear gpin extending transversely through the anvil and into-the frame for holding the'anvil in operative position, means for, guiding a mine line into the space between the cutting member and anvil, and explosivemeans for driving" the cutting'mcmber through said line and against the lanvilywhereby said pin is sheared off and'the anvil and cutting member shoot out of the frame. 18. A r'nine anchor-line cutter comprising atframe, a

' free cuttin'gtmember rslidably mounted in the frame, an

anvil spaced from-the cutting end of said member, a shear pin-extending transversely through the anvil and into the frame for holdingthe anvil in operative position, means for: guiding a mine line intothe space between the cutting member and anvil, explosive means for driving v the cutting member through said line and'against the ;anvil-,..whereby said pin is sheared otfan dthe anvil and shear spin extending transversely through ,the- [anvil and? into theiframefor holding the anvil in ope'rativeposition, meansforw guidiiig amine line into the space betweenthe cuttingfimemberzand anvil, explosive; means for driving; the cutting member through 1 said line and against" the; anvil, wherebysaidpinis shearedzoffi-iand theanvil and: cutting member. leave the t-frarrie, and -means ,normally held retractedby said, pin for closing the entranceto said space .after the pin-hasbeen sheared off ,j 5 -20; fA mine rancher-line cutter-comprising a frame, a free cutting member; sllidably mounted in the frame, an anvil spaced from the cutting end Zof said -rnember, a shear pin extending transversely through the anvil and into the frame forholding the anvil inoperative position, means for guiding'a mineline into the space-betweenthe cutting-member and -anvil,-said pin havingarhead, means "for" closing the rentrance to saidspacenormally: held in open position by said head, and explosive means for driving the "cutting -member through said line and against theanvil, whereby said pin is sheared'off and its head releases saidspace-closingmeans. 7 y

21. l A. mine anchor-line cutter comprising a frame, a cuttingunember carried by the frame, said frame being provided -with a recess-adjacent-the cutting end of said member for receiving a mineline, explosive means for; driving the cutting-member through said line, and means for closing the entrance to said recess after'the line has been cut. 7

22. A-mine anchor-line cutter -comprising a'frame a cutting member carried by the frame, said frame being provided with-a =recess adjacent the cutting end-of said member, a guide member-movably attached totheframe for guiding a mine line into-said recess,.explosive means for driving the cutting member-throu'ghsaid line, and

means for moving said guide member across the ,1 en

trance to :said recess after thejline'has beencut,

v23. A mine ianchor-line cutter comprising a frame,a cutting member carried by the frame, saidframe-being provided with'a recess adjacent-the cutting end of said member, a normally: open gate pivotally connected'to the frame beside said recess, explosive means for: driving the cutting member through said line, and means :for swinging said gate across the entrance-to said recess after theline has been cut.

24. A mine anchor-line cutter comprising satframe, a cutting'member carried by the frame, said frame being provided with recess adjacent the'cutting end of said member, a gaterpivotally connectedtto the frame beside said recess, means normally holding'the gate open, ex-: plosive means for driving the cutting member through said line, the movin'gcutting member releasingisaidgate-holm ing means, and-means for swinging the released gate across the entrance to said recess; V L V 25. -A mine'anchor-line cfutter comprising a frame, a cutting member carried by theiframe, said frame being provided with a recess adjacent the cutting end of said member, a normally open :gate pivotally .connected to the frame beside said recess, explosive means fordriving the cutting member through said line, vand means for swingingsaid gate across the entrance tosaid recess after the line has been .cut, saidtgatet being shaped to straddle the cutting member in saidtreces's;

'26. A'mine anchor-line cutter'cornprising a frame, a cutting member carried. by' the frame, said frame being provided with atrecesswadjacent the cutting end of said member, a; gate pivotallytconnected to the frame beside .said recess, -a 'shear :pingextending across the path 'of .travel- :of-the cutting member andnormally holding the gate open, explosivemeansfforedriving the cutting memher. through; said .line, ;.the moving ;cuttingr.mem'ber causing the shear pin to be sheared off to release said gate, and means for swinging the released gate across the en trance to said recess.

27. A mine anchor-line cutter comprising a frame, a cutting member carried by the frame, said frame being provided with a line-receiving recess adjacent the cutting end of said member, a removable anvil in the end of the recess opposite to the cutting member, a gate pivotally connected to the frame beside said recess, a shear pin connecting the anvil to the frame and projecting from the frame, the projecting portion of the pin being formed to normally hold the gate open, explosive means for driving the cutting member through said line and against the anvil, the impact against the anvil causing it to shear ofi said pin whereby the anvil and cutting member can leave the frame and the gate is released, and means for swinging the released gate across the entrance to said recess.

28. A mine anchor-line cutter comprising a frame provided in its front side with a recess for receiving a mine line, a cutting member carried by the frame, explosive means for driving the cutting member across said recess to sever said line, and a fin on the forward portion of which said frame is mounted for holding the frame substantially horizontal while being towed through 10 the Water by a sweep line, the fin projecting forward beyond the front of the frame with its front edge substantially parallel to the sweep line and inclined back to the entrance of said recess for guiding mine lines to the recess.

29. A mine anchor-line cutter comprising a stabilizing fin adapted to be connected along its front edge to a sweep line, a frame mounted on said fin. at an acute angle to said front edge and with the frame projecting beyond said edge, the front of the frame being provided with a recess for receiving a mine line, said recess having its entrance extending forward from said front edge of the fin, a cutting member carried by the frame, and explosive means for driving the cutting member across said recess to sever a mine line therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,312,405 Lander Aug. 5, 1919 1,397,911 Tossizza Nov. 22, 1921 FOREIGN PATENTS 134,069 Great Britain Oct. 30, 1919 

